Hello everyone. I have a 78 k5 with a 203 transfer case that has been converted to part time 4 wheel drive. I have not used 4 wheel drive since I got it and realized an issue. No matter what it just makes a grinding noise and will not engage 4 wheel drive. What could be causing this? Thank y’all.
CK5
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Transfer case
- Thread starter CJ2
- Start date
203 shifters are notoriously problematic. You could disconnect the shift linkage from the tcase and manually engage it to see if it’s only partially engaged, it could be an adjustment issue.
That said, that could very well be the drive chain slipping on the front output shaft sprocket.
That said, that could very well be the drive chain slipping on the front output shaft sprocket.
The part time kits cause more problems than they fix, they starve the case of oil and over time the cogs that lock it get sloppy and allow play……I agree about the shift linkage, start there and see what happens, 203 parts are getting scarce, the chains haven’t been made in years.
Agreed with all above - if it turns out to not be a shifter linkage partial engagement issue then it’s time to consider another case.
It’s rarely recommended to put money into a tired 203 ( assuming parts can be found ) so a 27-spline 205 or a 208 ( later requires a trans output shaft length change ) just might be in your future.
It’s rarely recommended to put money into a tired 203 ( assuming parts can be found ) so a 27-spline 205 or a 208 ( later requires a trans output shaft length change ) just might be in your future.
When the front wheel hubs are unlocked the transfer case works fine. It shifts with no noise. When I put it in low the front drive shaft spins but won’t move the truck. I lock the hubs and it makes a grind noise coming from the hub not the transfer case. I distance 4 wheel and try to engage again now with the hubs locked and now the transfer case makes a noise. Also in 2 wheel drive and the hubs locked the truck makes a clunk noise. Could something be wrong with my front diff?
Very possible - start with the basics and simplest possibilities which would be the front hubs first, followed by axle joints and then the front differential.
Any issues with the front end can make diagnosing a T-case problem more difficult.
Question: when you say that once in low range the truck won’t move - does this do the same in FWD high range?
Also once the T-case is in 2WD and the front hubs are unlocked will the front driveshaft turn freely by hand ?
Any issues with the front end can make diagnosing a T-case problem more difficult.
Question: when you say that once in low range the truck won’t move - does this do the same in FWD high range?
Also once the T-case is in 2WD and the front hubs are unlocked will the front driveshaft turn freely by hand ?
Answer 1: yes, it does the same in high range. When put in drive the drive shafts spins. I press on the gas and the drive shaft spins faster but does not move. The back wheels should move though? (Front hubs are on free so makes since the front are not)
Answer 2: good question. I’ll have to check this.
Also when the front is in the air, and hubs are locked the wheels spin with the driveshaft in sequence with no noise.
Answer 2: good question. I’ll have to check this.
Also when the front is in the air, and hubs are locked the wheels spin with the driveshaft in sequence with no noise.
Could it be possible that the previous owner didn’t actually install a part-time kit in your 203 but rather just installed manual hubs and has been driving in high-lock position?
You may very well have other issues but it is sounding like the T-case is functioning like a true full-time unit by your descriptions.
This would not be the first time that someone found out that their 203 was not really converted over to part-time…
You may very well have other issues but it is sounding like the T-case is functioning like a true full-time unit by your descriptions.
This would not be the first time that someone found out that their 203 was not really converted over to part-time…
In a 203 truck that hasn't been converted the truck will not move if the hubs are unlocked. The truck can also roll away in park if the hubs are left unlocked.
What about the two “locked” positions for high & low range as opposed to the street friendly normal high & low range “full-time” positions of the 203 case ?
Shifter selections were ( not in this order ) originally:
High range - full-time
High range - locked
Neutral
Low range - full-time
Low range - locked
For a total of five selectable positions.
Either range selected in the locked position and the diff in the back half of the 203 was locked and no longer allowed the open type differential operations.
Pics are from a 1974 model year factory GM brochure and shows the two “locked” positions and mentions using them in the script.
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I think it has been converted. The transfer case is in the normal high position for 2 wheel drive. Also the front drive shaft does not move while driving in 2 wheel drive. When in high lock a light on the dash turns on.
Something is broken in that front end. go there first.
When the hubs are unlocked and t case is in 2 wheel drive the front drive shaft will not spin by hand. It does when the t case is in the 4 wheel drive position though. When I spin the drive shaft while the t case was in 4 wheel drive the left wheel u joint would spin, but not the right wheel.
Could the rears have different ratios?
I should have clarified, if not in locked position. A lot of people pulled the front shaft (or added hubs) and drove around in 4 loc as a way to increase MPG, which it really didnt and instead added wear to the differential inside the tcase.
